String-up device



Patented Dec. 26, 1949 STRING-UP DEVICE Edward N. Lichtenberg, Wilmington, Del., as-

signor to E1. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware 7 Application June 17, 1948, Serial No. 33,523

12 Claims.

1 This invention relates to the draw twisting of artificial fibers and particularly to a device for stringing-up machines used for the continuous draw twisting of artificial fibers.

Artificial fibers, such as those sr 1". from melts of the linear polyamides, possess t relatively low tensile strength and a high elongation as extruded from the forming spinneret. It has been found that the tensile strength may be greatly increased and the elongation characteristic correspondingly reduced by a process of cold drawing whereby the yarn or monofilaments are stretched to the extent of 400 to 500% of their original lengths and subsequently stabilized by exposure to elevated temperatures below the melting point of the material. The cold drawing operation described may be conveniently effected by passing the artificial fibers over a feed roll and thence over a draw roll rotating at a peripheral speed in the range of 400 to 500% of that of the feed roll, or preferably by passing the yarn or monofilament over a snubbing pin interposed between the two rolls for the purpose of localizing the drawing action in the manner disclosed by Babcock in U. 8. Patent 2,289,232. The drawn yarn is then taken up by a rotating bobbin, fitted with a ring traveler or like device, which is assembled on a common frame with the feed roll and the draw roll.

The draw twisting of yarns, particularly low denier yarns, necessitates the use of considerable equipment for the manufacture of commercial quantities of product. It is desirable to employ relatively long lengths of shafts for the drawing, using a single length to accommodate as many as twelve drawing positions and spacing successive positions as closely together as possible to economize on building space, and, at the same time, facilitate the labors of machine tending. Such a machine is commonly referred to as a continuous shaft type drawing machine, it being understood that service can be extended to any number of individual positions by mounting additional lengths of draw shaft in prolongation with one another, each providing the drawing for a multiple number of positions. The yarn being manufactured sometimes breaks under the strain of the drawing process, and it is then necessary that the operator restring the draw roll to restore operation at this position. With the low clearances attaining, stringing-up by hand cannot be accomplished without hazard to personnel while, if the machine is shut down temporarlly to remedy the break at one position, the production time at all the other positions is lost.

A principal object of this invention is to provide a safe process and device for stringing up yarn on continuous type draw twisting machines while the machines are in operation.

Another object of this invention is to provide an economical improvement for stringing up yarn around a continuous rotating shaft.

Other objects of this invention will become apparent when considered with the description as illustrated by the accompanying drawing in which:

Figure 1 is a diagrammatic front elevation view of an assembly of equipment for the continuous draw twisting of yarn showing two drawing positions, each fitted with a string-up device according to this invention, and indicating by broken line representation the position of the yarn during the drawing operation.

Figure 2 is an end elevation view of the assembly of equipment shown in Figure 1.

Figure 3 is a detailed side elevation view of one embodiment of string-up device according to this invention showing by broken line representation the position of the yarn preparatory to transfer to the draw roll.

Figure 4 is a sectional view taken along line 4-4 of Figure 3.

Figure 5 is a sectional view of one embodiment of a ring retaining member showing a preferred method of connection to the draw twisting machine.

Figure 6 is an enlarged view of pin l1, shown in Figures 3 and 4.

In general, the objects of this invention are accomplished by providing a freely rotatable support in encircling arrangement with the continuous draw roll, whereby the yarn end may be threaded about the draw roll while no tension is being applied to it and then readily engaged with the rotating draw roll when a sufiicient number of turns have been accumulated to prevent slippage of the yarn on the draw roll.

Referring to Figures 1 and 2 a typical continuous draw twisting machine comprises a conventional machine frame (not here shown) which supports the yarn supply packages 2, yarn tensioning devices 3, traversing thread guides: 4, top rolls 5, continuous feed roll 6, draw pins 1, continuous draw roll 8, separators 9, thread guides 10, and wind-up bobbins ll. Each bobbin is fitted with a conventional ring traveler or like device (not here shown) to impart the desired amount of twist to the yarn in the course of wind-up operations and to control the tension in the yarn prior to its collection on the bobbins.

In operation, the yarn to be draw twisted is pulled from the supply packages 2 by the friction of the rubber covered to rolls 5 which bear on positively driven feed roll 6. and each position is thereby'supplied with a single length of yarn moving at a preselected velocity. The reciprocation of traversing guides 4 continually shifts the 4 bar wrenches. The retainers are drilled to provide an oversized passage 22 for the reception of the bolt shanks and are counter-bored to provide a correspondingly oversized passage 28 for the bolt heads, whereupon it will be apparent that the positions of the retainers may be readily ad- Justed over a relatively wide range by varying the yarn track over top rolls 3, thus minimizing roll.

surface wear. The yarn leaving the feed roll is looped twice around the draw pins 1 and then wrapped a suflicient number of times around the draw roll 8 to prevent slippage thereon as this roll is positively rotated in the same direction as the feed roll. The diameters and speeds of rotation of rolls 8 and 8 are so chosen that the ratio of the peripheral velocity of roll 8 to the peripheral velocity of roll 6 will be the same as the degree of drawing which it is desired to effect. Thus, for a draw ratio of 4 to 1, for example, the peripheral velocity of roll 8 should be 400% that of roll 8. Separators 9 are rollers which are canted slightly forward in the same horizontal plane as the axis of draw roll 8, so that each wra of yarn passed over the separators from the underside of the draw roll will be slightly advanced from its predecessor, and yarn overlapping will thereby be avoided. Generally, three complete wraps of the yarn around the draw roll and separator will be sufficient to prevent yarn slippage on the draw roll so that the yarn will be positively delivered to the bobbins II at a substantially constant velocity equal to the peripheral velocity of draw roll 8. The drawn yarn is guided to the bobbins by thread guides l0, being passed through conventional ring traveler devices or the like prior to winding up. The yarn may also be dimensionally stabilized after drawing by leading it over a heated platen or like means interposed in the yarn path after the yarn's traverse of the draw roll.

In the event that a single yarn strand breaks in the course of drawing, it will be understood that the positively driven wind-up bobbins II will rapidly take up the free yarn until no wraps remain in place around the draw roll and separators. Any yarn which is thereafter supplied by feed roll 6 usually entangles around draw roll 8 or collects on the necked down portion between adjacent roll faces, from which it is cut away and discarded as waste. Before operation can be resumed at the position, it is necessary to restring the yarn about the draw roll and separator, and reconnect the free end about the bobbin.

This restringing operation is conveniently effected according to this invention by means of a rotatable collecting ring l3 which is mounted on the machine frame in encircling relationship to draw roll 8 and separator 9, and slightly offset from the normal course of yarn travel through the machine to prevent interference with the yarn during normal operations.

Referring to Figures 3, 4 and 5, ring I3 is rotatably supported from the underside by two flanged retainers l4 and is restrained from vertical movement by an identical retainer 15 located along the top edge of the ring at the vertical center line thereof. The three retainers are preferably disposed at an angle of about 45 degrees apart, measured from the center of ring [3, to provide maximum stability of support and, at the same time, prevent any binding action as the ring is made to turn about the draw roll and its associated separator.

As shown in Figure 5, the retainers are preferabutment of the bolt head with respect to the shoulder connecting the two passages. With the bolt seated at the bottom of the shoulder (as illustrated) the retainer occupies a position which is elevated by the amount of the full oversize dimension provided. Generally, an oversize drilling of about one sixteenth inch magnitude provides suilicient clearance for the purposes contemplated.

Ring I3 is preferably provided with four horizontally disposed pins secured thereto at equal distances around the edge at such intervals that yarn supported thereon preferably will at no point contact the draw roll as ring i3 is rotated. However, a limited contact is not objectionable so long as the yarn is maintained out of driven relation with the draw roll. The yarn may contact the separators during string-up, but it is preferable to limit this contact to not more than about 5 degrees to minimize stretching of the yarn. The pins of ring 13 are preferably radially disposed from the inner periphery a sufllcient distance to clear the flanges of the retaining members without contacting them. The three pins indicated at iii are preferably somewhat rounded at the ends to facilitate the ready transfer of yarn from the pins to the draw roll and separator. The fourth pin, [1, is slightly longer than the other three and is provided with a cleft end to facilitate engagement of the yarn therewith. Hooked pins l8 disposed with their open ends forward above draw pins I serve as guides for the yarn during the stringing-up operation.

The operation of the string-up device of this invention will now be described with particular reference to Figure 1. The free end of the yarn is first led over the tension device 3, through guide 4 and then inside pin l8, after which it is wrapped twice around draw pin 1. The free end is then caught in the cleft end of pin l1, and ring I: is turned through three revolutions in the same direction as the draw roll is rotating. The precise degree of rotation necessary to accumulate three wraps of yarn around pins l6 and I! may be easily indicated by painting a reference line across the peripheral surface of the ring as a point adjacent to 'pin ll, whereby the operator can readily determine by visual inspection the extent to which the ring is rotated.

When three wraps of yarn have been accumulated on ring Hi, the operator disengages the end from cleft pin l1 and pulls it through thread guide III, the yarn being readily stretched in the course of this step because it has not yet been subjected to drawing. Each of the bobbins Il may be provided with a suitable knee brake (not here shown) which, when manually depressed, engages a friction disk with the bobbins drive whorl and brakes the-bobbin tu a complete stop. With the bobbin brought to a standstill the operator loops the free end of the yarn several times around it and also loops the thread through the traveler. The yarn is then freed from hooked pin I8 and the knee brake is released, whereupon bobbin H resumes rotation and exerts tension on the yarn, making it imperative to perform the other steps of the string-up operation speedily. The yarn is threaded around the unobstructed side of top roll 5, which is mounted on a swing arm so that this operation may be effected while roll is at rest and out of contact with feed roll 6. The yarn is readily transferred from the pins of ring I3 to draw roll 8 and separator 9 by merely flipping the three wraps clear of the long pin ll, whereupon the yarn will at once be drawn free from pins I6 and the slack will be taken up by the tension in the yarn exerted by the ring traveler associated with the bobbin. Simultaneously top roll 5 is swung forward so that it rests against the surface of feed roll 6 and is driven by it, whereupon the drawing position is completely restored to normal operation.

It will be apparent from the foregoing description that the string-up device of this invention makes it possible to rapidly correct failure of operation due to yarn breakage, or entanglements necessitating breaking the yarn, without exposing personnel to the dangers of contact with the moving machine parts. The device possesses advantages of low first cost and maintenance and may be readily combined with standard yarn drawing equipment without requiring any substantial modifications or alterations thereto.

While the precise construction hereinbefore described is preferred, it will be understood that the form and number of the yarn supporting pins l6 and I! may be widely varied to meet particular requirements. Also, ring l3 may be of separable hinged construction so as to be conveniently assembled or removed from encirclement with the draw roll and may have a variety of cross-sectional shapes. within the spirit of this invention will become apparent from the foregoing detailed description and the invention is to be limited only to the extent indicated in the following patent I claim: i

1. A process for stringing up yarn on a continuous, shaft-type draw-twisting machine while the machine is in operation comprising temporarily accumulating lengths of yarn in encircling relationship but out of driving contact with the draw roll and transferring said accumulation to the draw roll.

2. A process for stringing up yarn on a continuous, shaft-type draw-twisting machine while the machine is in operation comprising gathering the thread in loops on a rotating element in encircling relationship but out of contact with the draw roll, and transferring the loops to the draw roll.

3. A process for stringing up yarn on a continuous, shaft-type draw-twisting machine while the machine is in operation comprising accumulating lengths of yarn on a rotatable support in encircling arrangement but out of contact with the draw roll and then engaging the yarn with the rotating draw roll when snflicient turns of the yarn have accumulated to prevent slippage of the yarn on the draw roll.

4. A process for stringing up yarn on a continuous, shaft-type draw-twisting machine while the machine is in operation comprising engaging the free end of the yarn with one of a series of points on a rotatable element supported independently of the'draw-roll element but in encircling relationship but out of contact with the draw roll, engaging loops of the yarn at the remaining points of the series to form a multi- 75 Other modifications plicit of loops of the yarn and transferring said loops to the draw roll.

5. In a yarn drawing machine embodying a draw-roll element, a string-up device comprising a rotatable means supported independently of the draw-roll element but in encircling relationship therewith, said means having a second means for the temporary accumulation of a length of yarn out of driving contact with said draw-roll element at positions assumed by said first means during its rotation.

6. In a yarn drawing machine embodying a draw-roll element, a string-up device comprising a rotatable ring supported independently of the draw-roll element but in encircling relationship therewith, said ring having means for the temporary accumulation of a length of yarn out of driving contact with said draw-roll element at the various positions assumed by said ring during its rotation.

'7. In a yarn drawing machine embodying a draw-roll element, a string-up device comprising a rotatable ring supported independently of the draw-roll element but in encircling relationship therewith, said ring having a series of supporting means disposed substantially equidistantly along the edge thereof at such intervals that yarn engaged by the successive means is out of driving contact with said draw-roll element at the various positions assumed by said ring during its rotation.

8. A string-up device according to claim '7 wherein at least one of said series of supporting means is provided with a further means for positive engagement with and retention of the yarn.

9. In a yarn drawing machine embodying a draw-roll element, a string-up device comprising a rotatable ring suported independently of the draw-roll element but in encircling relationship therewith, said ring having a series of pins disposed equidistantly along the edge thereof at such intervals that yarn wrapped around the successive pins is out of driving contact with said draw-roll element at the various positions assumed by said ring during its rotation.

10. A string-up device according to claim 9 wherein at least one of said plus is provided with means for positive engagement with and retention of the yarn.

11. In a yarn drawing machine embodying a draw-roll element and an associated separator element, a string-up device comprising a rotatable ring supported independently of the draw-roll element but in encircling relationship therewith and with said separator element, a plurality of pins disposed equidistantly along the edge of said ring at intervals such that yarn wrapped around successive pins is out of driving contact with said draw-roll element at various positions assumed by said ring during its rotation, and that yarn contact with said separator element is substantially within an angle of about 5 degrees.

12. A string-up device according to claim 11 wherein the rotatable ring is supported and restrained by a plurality of flanged retaining members disposed around the periphery, said retaining members having oversized holes for the reception of the shank portions of retaining bolts. and counter-bored, oversized, coaxial holes 'for the reception of the head portions of said bolts. whereby adjustments in the position of said ring may be effected by altering the position of abutment of the retaining bolts upon the shoulders formed by the joinder of the two 'oversized holes.

EDWARD N. LICHTENBERG.

No references cited.

Certificate of Correction Patent N 0. 2,491,569 December 20, 1949 EDWARD N. LIOHTENBERG It is hereby certified that error appears in the printed specification of the above I numbered patent requiring correction as follows:

Column 3, line 8, for top rolls 3 read top rolls 5;

end that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice. Signed and sealed this 18th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gommissioner 0f Patents. 

